US Patent 8127165 Multipath power management

Disclosed is a method of controlling power. Multiple paths via multiple I/O ports couple a server to a storage array. When I/O loads are low, it is determined if an I/O port may be deactivated and placed in a power saving mode. An I/O port may not be deactivated if deactivating that I/O port will affect a high-availability requirement or a performance requirement. Requests are stopped from being sent to an I/O port to be deactivated. When the port to be deactivated becomes idle, the I/O port is placed in a power saving mode. When I/O loads increase to a point where it is necessary to reactivate the I/O port, the I/O port is activated.